User's Manual
Table Of Contents
- 1 Disclaimers
- 2 Safety information
- 3 Notice to user
- 4 Customer help
- 5 Quick Start Guide
- 6 List of accessories and services
- 7 Description
- 8 Operation
- 8.1 Charging the battery
- 8.2 Turning on and turning off the camera
- 8.3 Saving an image
- 8.4 Recalling an image
- 8.5 Deleting an image
- 8.6 Deleting all images
- 8.7 Measuring a temperature using a spotmeter
- 8.8 Measuring the hottest temperature within an area
- 8.9 Measuring the coldest temperature within an area
- 8.10 Hiding measurement tools
- 8.11 Changing the color palette
- 8.12 Working with color alarms
- 8.13 Changing image mode
- 8.14 Changing the temperature scale mode
- 8.15 Setting the emissivity as a surface property
- 8.16 Setting the emissivity as a custom material
- 8.17 Changing the emissivity as a custom value
- 8.18 Changing the reflected apparent temperature
- 8.19 Changing the distance between the object and the camera
- 8.20 Performing a non-uniformity correction (NUC)
- 8.21 Configuring Wi-Fi
- 8.22 Changing the settings
- 8.23 Updating the camera
- 9 Technical data
- 10 Mechanical drawings
- 11 CE Declaration of conformity
- 12 Cleaning the camera
- 13 Application examples
- 14 About FLIR Systems
- 15 Definitions and laws
- 16 Thermographic measurement techniques
- 17 History of infrared technology
- 18 Theory of thermography
- 19 The measurement formula
- 20 Emissivity tables
Theory of thermography
18
• A selective radiator, for which ε varies with wavelength
According to Kirchhoff’s law, for any material the spectral emissivity and spectral absorp-
tance of a body are equal at any specified temperature and wavelength. That is:
From this we obtain, for an opaque material (since α
λ
+ ρ
λ
= 1):
For highly polished materials ε
λ
approaches zero, so that for a perfectly reflecting materi-
al (i.e. a perfect mirror) we have:
For a graybody radiator, the Stefan-Boltzmann formula becomes:
This states that the total emissive power of a graybody is the same as a blackbody at the
same temperature reduced in proportion to the value of ε from the graybody.
Figure 18.8 Spectral radiant emittance of three types of radiators. 1: Spectral radiant emittance; 2: Wave-
length; 3: Blackbody; 4: Selective radiator; 5: Graybody.
Figure 18.9 Spectral emissivity of three types of radiators. 1: Spectral emissivity; 2: Wavelength; 3: Black-
body; 4: Graybody; 5: Selective radiator.
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